Estimating global exposure and risk of transport networks to natural disasters

Estimating global exposure and risk of transport networks to natural disasters

By Anna Halworth

Reliable transport infrastructure is one of the backbones of a prosperous economy, providing access to markets, jobs and social services. However, natural hazards – such as surface, river and coastal flooding, hurricanes and tropical cyclones – can significantly impact the functioning of transport infrastructure. The economic consequences of transport disruptions due to extreme events often go well beyond direct infrastructure damage, also including increased travel costs and time, impaired trips and supply chain disruptions.

Research recently published finds that damage to road and rail infrastructure due to natural disasters could result in average annual costs of approximately $14.6 billion, globally. However, the research team also found that small additional investments at planning stage result in dramatic savings when natural disasters hit. “The benefits of the additional cost of building in more resilience (about 2%) can easily be offset by higher efficiency in spending and service delivery, which can halve total spending needs,” explains co-author Dr Conrad Zorn, of the University of Oxford and ITRC-MISTRAL.

In this study, researchers used state-of-the art global hazard mapping, combined with innovative analysis of approximately 50 million km of transport network data included in OpenStreetMap, and assumptions about the fragility and (re)construction of transport infrastructure derived from a variety of sources. The exposure and risk of these assets was assessed for the most frequently recorded and costliest disasters: tropical cyclones, earthquakes, surface flooding, river flooding and coastal flooding.

This analysis finds that just below a third of all global road and railway assets are exposed to at least one hazard, and that about 8% of all assets are exposed to a 1-in-100 year flood event. Road and rail networks are most exposed to surface flooding, followed by tropical cyclones, river flooding, and earthquakes. As exposure is driven by both the occurrence of hazards and the existence of assets, high-income countries with more transport infrastructure can be expected to be more exposed, with US, Japan and those in Europe specifically identified. Indeed, for surface flooding, richer countries with more assets are proportionally more exposed. However, for river and coastal flooding, high-income countries have fewer exposed kilometres because of the higher flood protection standards in these countries.

When expected annual damages are considering in relation to GDP, infrastructure value or infrastructure length, low and middle-income countries are often more severely affected. For example, in Small Island Developing States, annual damages relative to total infrastructure value are more than double the global average. Furthermore, when countries like Fiji already spend 30% of their government annual budget in maintaining their transport network, the bill becomes prohibitive when damages from natural hazards are added to this. In other words, for several countries and regions, investing in transport asset resilience should be a priority.

The study concludes by stating that adding resilience to transport planning, such as improved road design for better drainage and including flood barriers at planning stage, could reduce worldwide damages by up to 60% and save billions of dollars. With climate change likely to intensify the impacts of natural hazards on transport infrastructure, there has never been a more crucial time for countries to improve their transport planning by including physical climate risk information in their assessments.

Over recent years, Acclimatise has delivered a number of national-scale transport climate resilience projects, including in the Caribbean, Serbia and Tanzania. We have developed a number of robust analytical methodologies for undertaking climate change and natural hazard risk assessment for transport networks. Through the systematic identification of spatial ‘hotspots’ of risk, improvements can be targeted to the areas of most need, which will ultimately reduce infrastructure spend and better future-proof assets to prevent damage from natural hazards.

The full Nature Communications article is available here

If you would like to discuss our capabilities in the transport sector and analytical tools, please contact Bob Khosa

Cover photo by Ian Britton on Unsplash.

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